Tuning means for radio receivers and the like



1949. I R. c. WILKS 2,479,658

TUNING MEANS FER RADIO RECEIVERS AND THE LIKE Filed Sept. 21, 1945 Patented Aug. 23, 1949 TUNING MEANS FOR RAD) RECEIVERS A D THE L KE Roy Coles Wi'l'ks, South Yarra, Victoria, Australia Application September 21, 1.945, Serial No. 617,804

Australia March 29, 1945 2 Glaims. 1

This invention relates to tuning means for radio receivers and the like and has particular reference to the .means for operating the dial indicator .or pointer in synchronism with the tun- 111g means.

More especially the invention relates to a device according to my U. S. Patent No. 2,364,765, which includes an indicator pointer connected to a nut member which encircles a screw-threaded rod having a dri ing connection with the adtiustable element of the tuning means, provision being .made .to prevent the .nut member from turning with the screw-threaded rod so that when the latter is rotated to adjust the tunin means, the nut member will be moved along the screwed rod and impart corresponding movement to the indicator pointer.

My aforesaid specification also discloses an automatic stop device adapted to resist overturning of the operating rod after the tuning means has reached its extreme adjusted positions.

My patented devices "have been found to be very eflicientand generallysatisfactory in operation, but I find that it is still possible to improve their operating characteristics ;by providing means whereby the turning knobof the screwed rod is released from the latter upon the tuning means reaching either of its extreme adjusted positions.

"While the automatic stop device previously reterred to is generally effective in operation, it might yet be that a determined attempt to turn the operating knob after the tuning means has reached one of its extreme position would lead to the pins of the stop device being broken, whereupon serious damage and misalignment wouldari-se.

This deficiency is overcome by the presentimmovements in a simple and efiicientmanner as will be readily appreciated hereinafter.

According to the presentimprovements, I proride :a connection'between the turning knoband the screwedoperating rod which is normally a fast driving connection but which, upon the automatic stop. device cominginto'play, will be automatically caused to slip, so that continued turning of the operating knob will not be communicated toethe screwed rod.

A construction which is at present preferred will now be described with reference to the accompanying drawings, inwhich- Figure 1 is a side elevation of radio tuning means incorporating the present improvements.

Figure-21s an enlarged elevation of a nut memberand-associated-parts.

Figure 3--is a cross section of Figure 2.

Figure 4 is a sectional view on line f'IV.'IV.of Figure 3.

5 is a sectional elevation of a driving .cheapness compared with an equivalent screwed shaft which is milled to high precision standards. As will appear hereinafter extreme accuracy and uniformity in the formation of this screw threaded portion is not essential .for the reason that such irregularity as may exist will be fully compensated for by the improved nut member.

This nut member .1 is formed of two halves or sections 1a and .11) which extend lengthwise of the rod .6, and the semi-circular interior of each section is internally screw threaded in a manner complementary tothe screw threaded portion Ba of the .rod.

Both sections of the nut member are provided adjacent their opposite ends with two circumferential-ly extending grooves .3 within each of which is accommodated a coiled spring 9. The ends III of eachspring 9 are connected to a tension adjustment plate H which extends lengthwise adjacent .one .of the nut sections, preferably the rear nut section lb. This nut section is provided with an outstandin guide pin 12 which passes freely into a guide hole formed in the tension adjustment plate VI 1. This plate is also provided with screw threaded holes, one on each side of the guide pin, to receive adjusting screws .13.,the inner end of which bear against the exterior of the rear nut section 1b which may have small depressions to receive the inner ends pf thescrews.

By tighteningor slackening one or other of the screws :13, the tension of the springs .9 will be controlled so as to cause the nut sections to 'be resiliently clamped with any desired degree of pressure around the screw threaded portion of the shaft. in this manner, tolerance or back lash between the nut member and the screw thread or irregularity in the formation of the latter can be overcome by initial adjustment and/or by the automatic resiliency provided-Joy thespringszand associated parts.

The indicator pointer M may be attached at its inner .end ,by screws or the like 2130 one of the nut sections and preferably the rearmost section 1b.

ilothis samenutseetion lbthere may also be attached a "depending guide 4&6 whichis adapted at its lower or rear end to slidably engage a slotted rod ii that extends parallel with the screw threaded rod 6. This slotted rod and the operating rod may be supported at the ends by columns l8 attached to the chassis l9 of; thereceiver.

The depending guide member may take various forms. According to one example it may consist of a strip 2! of flat sided or rectangular shape which projects into the slotted rod and is capable of being turned about a perpendicular axis,- as by being connected at its upper end by a screw and nut 22 to its nut section lb, whereby it may be ensured that opposite edges of the slot in the rod will be engaged by opposite edges of the guide strip. Such an arrangement ensures that the nut member will be prevented from any side play or wobbling and will be effectively guided in its lengthwise movement consequent upon rotation of the screw threaded shaft.

Referring now to the drive between the screw threaded rod and the adjustable element of the tuning means e. g. a gang of condensers 23, this driving connection combines the functions of a toothed gear drive and a friction drive. In explanation thereof it may be pointed out if a toothed gear drive alone is used then it is practically unavoidable that back lash will occur be,- tween the toothed gears. If, on the other hand, the drive is effected solely by friction, then creeping would be likely to arise. Either of these faults would prevent synchronisation between the driving means and the dial indicator from being maintained indefinitely.

According to a preferred construction of the combination drive as more clearly illustrated in Figures 1 and 5 of the drawings, the tuning condenser spindle 265 has affixed thereto a disc 26 which for a portion of its periphery is provided with gear teeth 27. This toothed portion meshes with a toothed pinion 28 which may be formed on a fly wheel that is secured to sleeve or bush 29 which in turn is made fast to the operating rod 6. This pinion 28 is surrounded by an annular fiange 3!, that is integral with the sleeve 29. A nut 32 which screws on to one end of the sleeve 29 provides a bearing face for one end of a spring 33 which presses a collar 34! into engagement with flange 3|. To ensure that the position of the nut 32 will be secured at a predetermined position on the sleeve 29 a screw 36 is adapted to bear upon the screwed portion of the sleeve 29. A flywheel 3'? is attached to an extension of the sleeve 2% to make the travel of the indicator pointer iii substantially even and devoid of any jerky movements.

' The pinion is thus almost completely concealed by and between the flange'Sl and the collar 34 which are yieldingly pressed into engagement by the spring 33. However, the toothed portion of the disc 26 on the condenser spindle 24 projects between the inner faces of the flange and the collar in order to mesh with the pinion 23.

Thus it will be seen that the drive is effected partly by intermeshing of the two toothed members 26, 28 and partly by the frictional grip created by the compression spring 33 causing the collar 3d and the annular flange 3| to closely engage opposite faces of the peripheral portion of the toothed disc 26.

The automatic stop device for resisting continued turning of the operating rod after the tuning means has reached either of its extreme adjusted positions is advantageously as disclosed in my aforesaid Patent No. 2,364,764.

Referring now to the connection between the turning knob and the screwed operating rod, a

4 preferred construction and arrangement is shown in Figures 1, 6 and 7. According thereto, the operating rod 6 is provided near one end with a plate or disc member 38 which may have a hub 39 by which it is secured, as by set screws to the rod. Disposed face to face with this fixed plate or disc, is another plate or disc ll which is considerably wider or thicker than the first disc,

and encircles the operating rod 6 without being attached thereto. The bore of the second disc is substantially greater than the diameter of the operating rod, but such disc is maintained concentric therewith by fitting around a reduced cylindrical neck portion 32 of a collet or collar 43 which is also free torotate upon the operating rod. I l

A spring member 4 3 extends between the shoulder formed by the stepping of the collar and the outer face of the second disc. While this spring member may take various forms, I have, found it advantageous to employ a spring in the form of a spider, having a series of circumferentially spaced radially projecting tongues, Ma (Figure 7), the outer ends of which :bear in dimples 46 formed in the outer face of the second disc GI. The pressure of the spring 44. is sufficient to normally maintain the second disc 4i in driving engagement with the first orfixed disc 38, but permits of slip between the two discs as soon as the screwed rod fi'is prevented from further rotation by the automatic'stop device.

The operating knob ll, which may be of any suitable form, is attached to the outer end portion of the collar 43 by set screws or the like,

' while a washer i8 and a pin d9 may be fitted at the outer end of the collar in order to-prevent the latter from sliding rearwardly off the rod.

It is desirable to provide for adjustment of the spring pressure so that the actionof the driving connection will not be. too fierce norjtoo easy. For this purpose, a pin and slot device or the equivalent may be associated with the main part of the collar adjacent the spring member, in order to permit of lengthwise adjustment whereby the pressure of the spring againstthe second disc may be increased or decreased. In this connection, it is of importance that the second disc should be of sufficient width or thickness to permit the reduced neck of the collar to remain within the bore of the second disc at all positions of adjustment.

The aforesaid construction andarrangement of the connection between the turning knob and the screwed operation rod has the further advantage that it is inexpensive to produce as all of the metal parts may be formed from stock material or as stampings.

Having now described my invention, what I claim .as new and desire to secure by Letters Patent is: j

1. In an automatic stop device for a radio receiver of the type including tuning elements, a rotary screw-threaded operating rodoperableto set the tuning elements, a nut having screwthreaded cooperation with said rod, means for preventing turning of said nut so thatit will move lengthwise along the rod when the latter is turned, an indicator pointer secured at one-end to said nut, a'stop device for resisting continued turning of said rod after the nut has reached its extreme positions along said rod, a manually operable knob for turning said rod, and connecting means between said knoband said rod and normally'providing'a driving connection there: between but being operable, upon actuation of said stop device, to slip so that continued turning of the knob will not be communicated to said rod, said connecting means including a first disc secured to said rod, a second disc freely surrounding said rod and disposed face to face with said first disc, a collar freely surrounding said rod and prevented from movement off the adjacent end thereof, the turning knob being secured to said collar, said collar having a reduced portion providing a shoulder between the second disc and said turning knob, and a spring extending between said shoulder and the face of the second disc remote from the first disc.

2. In an automatic stop device for a radio receiver of the type including tuning elements, a rotary screw-threaded operating rod operable to set the tuning elements, a nut having screwthreaded cooperation with said rod, means for preventing turning of said nut 50 that it will move lengthwise along the rod when the latter is turned, an indicator pointer secured at one end to said nut, a stop device for resisting continued turning of said rod after the nut has reached its extreme positions along said rod, a manually operable knob for turning said rod, and connecting means bet-ween said knob and said rod and normally providing a driving connection therebetween but being operable, upon actuation of said stop device, to slip so that continued turning of the knob will not be communicated to said rod, said connecting means including a first disc secured to said rod, a second disc freely surrounding said rod and disposed face to face with said first disc, the bore of the second disc being substantially larger than the diameter of that portion of the rod which it encircles, a collar freely surrounding said rod and prevented from endwise movement off the adjacent end thereof, the turning knob being secured to said collar, said collar having a reduced neck projecting into the bore of said second disc in order to maintain the latter concentric about the rod, a shoulder being formed at the rear end of said reduced neck, and a spring of spider formation having a central part bearing against said shoulder and the outer ends of radiating tongues bearing against the adjacent face of said second disc.

ROY COLES WILKS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,023,935 Riley Dec. 10, 1935 2,045,263 Cooper et a1 June 23, 1936 2,050,542 Pace Aug. 11, 1936 2,052,238 McDonald Aug. 25, 1936 2,105,639 Davis Jan. 18, 1933 2,345,910 Fawcett Apr. 4, 1944 2,364,764 Wilks Dec. 12, 1944 

